1294347 - Always use DirectWrite if available

Status: RESOLVED FIXED

(Core :: Graphics, defect)

Description

[David Anderson [:dvander] - inactive, e-mail if emergency]

The crux of the GPU process plan is that we shouldn't have any hardware-accelerated devices in the UI process. This means, as soon as we flip the switch, the UI process will no longer use DirectWrite for font rendering, but instead GDI.

My understanding is:
 (1) GDI does not look as good as DWrite.
 (2) We do not support DWrite + Cairo. bug 1193641 had evidence of breakage, but it's not clear whether that was busted D2D or something.
 (3) Skia is coming, and D2D and Skia are supposed to work together.

Is it time (or almost time) to just always flip DWrite on?

Comment 1

[David Anderson [:dvander] - inactive, e-mail if emergency]

s/D2D and Skia/DWrite and Skia/

Comment 2

[Jeff Muizelaar [:jrmuizel]]

Using Skia with DWrite should work better than Cairo and DWrite. However, it looks like Skia does take advantage of DWrite functionality that is only in the Win7 platform update and newer (IDWriteFontFace1) so we may want to limit our usage of DWrite to only Win7 platform update or newer. This matches what we do with D2D today.

Comment 3

[Mason Chang [Inactive] [:mchang]]

From the daily this morning: Let's always use Dwrite and Skia together unless on Windows XP because we have to use GDI there.

Comment 4

[Mason Chang [Inactive] [:mchang]]

Attachment: Use Dwrite with Skia backend by default

Comment 5

[David Anderson [:dvander] - inactive, e-mail if emergency]

Comment on attachment 8780230 [details] [diff] [review]
Use Dwrite with Skia backend by default

Review of attachment 8780230 [details] [diff] [review]:
-----------------------------------------------------------------

Thanks!

::: gfx/thebes/gfxWindowsPlatform.cpp
@@ +415,5 @@
> +  }
> +
> +  // DWrite is only supported on Windows 7 with the platform update and higher.
> +  // We check this by seeing if D2D1 support is available.
> +  FeatureState& d2d1 = gfxConfig::GetFeature(Feature::DIRECT2D);

d2d1 looks unused here. I think the Factory check is all you need anyway.

@@ -1601,5 @@
>      }
> -
> -    // Usually we want D2D in order to use DWrite, but if the users have it
> -    // forced, we'll let them have it, as unsupported configuration.
> -    if (gfxPrefs::DirectWriteFontRenderingForceEnabled() && !mDWriteFactory) {

You can drop this pref from gfxPrefs now (or keep it, and keep this block).

Comment 6

[Mason Chang [Inactive] [:mchang]]

Try looks good - https://treeherder.mozilla.org/#/jobs?repo=try&revision=d36800a4e0d5 - Updated with feedback from comment 5.

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/130d79a7ad56
Use Dwrite fonts with the skia backend by default. r=dvander

Comment 8

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/130d79a7ad56